1. Besides Formulary and Tech Chem (which doesn't have metaborate), where can you buy these? Are there any suppliers in Canada?

2. On Formulary's website, when you click on the details/MSDS for Sodium Metaborate it sends you to a Mule Team sheet indicating 4 Mol, Dihydrate. My understanding is in most photgraphic formulas it is assumed to be Octahydrate, so I'm a little confused.

3. Formulary's Borax also appears to come from Mule Team. Are these Mule Team borates really "photo grade" (ie are they good/pure enough for film developers)?

Thanks
Michael

04-08-2013, 10:32 AM

Ian Grant

1 & 3 I used to buy Borax direct from Consolidated Borax (20 Mule team) a few metric tons at a time, I used a small amount for my developers, it's the same as Photo grade but not analytical. Any good chemical supplier can get you Borax.

2 You'd need to ask the Formulary what version they are selling, Kodalk/Sodium Metaborate was the Octahydrate.

Ian

04-08-2013, 10:48 AM

Gerald C Koch

Hi Michael

Sodium metaborate has two hydrates. The confusion arises from how these hydrates are represented in formulas. Often the formulas are doubled making the tetrahydrate look like the octahydrate.

tetrahydrate NaBO2.2H2O also as NaB2O4.4H2O
octahydrate NaBO2.4H2O also as NaB2O4.8H2O

To distinguish between the two it is imporatant to not only look at the number of water molecules but also the number of boron atoms.

20 Mule team Borax is quite pure and can be used for photography. The term photo grade is misleading as it can be quite impure chemically. The only thing that photo grade gets you is a guarantee that the chemical contains no compounds the are injurious to the photographic process. It can still contain many impurities.

04-08-2013, 11:01 AM

Ian Grant

Qualifying the term Photo grade there's listings in books like LFA Mason, Photographic Chemistry, and elsewhere of the actual maximum levels of impurities in each chemical. I only have the BS Standards but they mirror the ASA/ANSI now ISO standards.

Purity is based on final use, food grade might be higher or lower than techniocal grade which is the industry norm, photograde is usually technical grade except for a few chemicals which may need to be purer and closer to analytival grade.

Ian

04-08-2013, 11:10 AM

Michael R 1974

Here is the metaborate formula indicated in the Mule Team link from Formulary:

NaBO2·2H2O [Na2B2O4·4H2O]

They refer to it as Dihydrate.

Interestingly Formulary also sells Balanced Alkali as a different product. I assume balanced alkali is Kodalk which would be the typical octahydrate form called for in developer formulas. I guess I'll have to ask Formulary.

Basically this all concerns a few experiments I wanted to try with a few typical versions of split D23-type developers. I've always stayed away from mixing my own developers but just want to try a few things for experimental purposes. One formula is the Stoekler version which calls for 10g/L Borax (assuming decahydrate) in the second bath, and the other one is the Adams version which calls for 10g/L Kodalk/Sodium Metaborate in the second bath, and that's the one where I'm not sure what type of metaborate to but in the second bath. I'd like to avoid overcomplicating this with conversion formulas etc if possible.

04-08-2013, 01:50 PM

Gerald C Koch

NaBO2 is what is known as a stoichiometric formula. It shows the relative proportions of the different elements. It does not indicate the actual structure which is more complex.